The general concepts, variables, and relationships described by the Interaction Model of Client Health Behavior (IMCHB) were used to guide a secondary data analysis of 203 women's decisions to request an amniocentesis. Step-wise multiple regression explained 58% of the variance in these decisions by jointly examining the factors which define the client as unique in her responses to an at-risk pregnancy, as well as factors describing the client-provider interaction. The women could be correctly classified as users or nonusers of prenatal diagnosis with 87% accuracy in a discriminant analysis based on the variables derived from the conceptual model. Finally, structural equation modeling was used to estimate the causal paths described by the general model. While the relationships proposed in the model need further empirical evauation, this first application serves to demonstrate the testability of the IMCHB and its potential to direct nursing inquiries.